A man looks at solar panels on a roof at Google headquarters in Mountain View, Calif.

Scientists are engaged in an increasingly bitter and personal feud over how much power the United States can get from renewable sources, with a large group of researchers taking aim at a popular recent paper that claimed the country could move beyond fossil fuels entirely by 2055.

In 2015, Stanford professor Mark Jacobson and his colleagues argued that between 2050 and 2055, the United States could be entirely powered by “clean” energy sources and “no natural gas, biofuels, nuclear power, or stationary batteries are needed.”

That would be a massive shift from the current power makeup, as in 2016, the United States got only 6.5 percent of its electricity from hydropower, 5.6 percent from wind and 0.9 percent from solar. Nonetheless, the paper excited proponents of renewable energy, and has been embraced by Sen. Bernie Sanders, celebrity backers such actor Mark Ruffalo and many environmental groups.

But Jacobson’s idea was always contentious. And now, no fewer than 21 researchers have published a study in the influential Proceedings of the National Academy of Sciences (which also published Jacobson’s original study in 2015) arguing that the work “used invalid modeling tools, contained modeling errors, and made implausible and inadequately supported assumptions.”

“We thought we had to write a peer reviewed piece to highlight some of the mistakes and have a broader discussion about what we really need to fight climate change,” said lead study author Christopher Clack, who is the founder of the firm Vibrant Clean Energy. “And we felt the only way to do it in a fair and unbiased way was to go through peer review, and have external referees vet it to make sure we’re not saying anything that’s untrue in our piece.”

Clack is backed in the study by a number of noted colleagues including prominent climate research Ken Caldeira of the Carnegie Institution, energy researcher Dan Kammen of the University of California at Berkeley, and former EPA Science Advisory Board chair Granger Morgan.

In a simultaneous letter in the journal, meanwhile, Jacobson and three Stanford colleagues fire back that Clack’s critique is itself “riddled with errors” and “demonstrably false.”

Jacobson also argued that his critics are biased in favor of carbon-based fuels such as oil, gas and coal, as well as nuclear energy.

“They try to falsify this thing by claiming that there are errors. This is what really bothers me with this paper. I don’t have any problem with people trying to quibble with our assumptions.”

The fight between researchers comes as the Trump administration has signaled it does not believe the nation’s electric grid can support a quick and thorough shift toward renewable energy, as Jacobson suggests that it can. As soon as this week, Energy Secretary Rick Perry is expected to release a study of the grid that renewable energy advocates fear will be used to criticize wind and solar and how they affect the grid.

The debate is crucial because, while it’s great to talk about wind and solar in theory, the reality is that the electrons that they generate have to be sent through wires and transmission stations to satisfy needs at particular places and at particular times — or else, we’ll have to come up with a way of storing electricity on a large scale, which remains a mostly unsolved problem right now.

And critics have contended that while you can add some wind and solar to the grid without any problem, if you add too much, it can be destabilizing and the electric grid will always require some “baseload” sources of energy, such as nuclear or coal or gas, which generate power continuously, rather than intermittently depending upon the availability of the sun or the winds.

In a 2015 study in the Proceedings of the National Academy of Sciences, Jacobson and his Stanford colleagues Mark Delucci, Mary Cameron and Bethany Frew laid out their clean energy vision. They used a model of the electric grid to show that the Lower 48 United States could be entirely powered by wind energy, solar power and hydroelectric energy, as long as there were various forms of energy storage available as well as “demand response,” in which major users of electricity are paid to curtail their use at key times when the grid is facing high demand.

The study also included a small role for geothermal energy and tidal and wave energy, the latter two of which are both fledgling technologies at this point.

Still, the study found that it could all work and, moreover, would be affordable. “The resulting 2050—2055 US electricity social cost for a full system is much less than for fossil fuels,” they wrote. The research, said Jacobson and his co-authors, should put to rest fears that adding large amounts of wind and solar to the grid would be destabilizing because these variable or “intermittent” sources of electricity would not always line up their production with the times when people need them most.

Particularly notable in the study was what Jacobson and his colleagues didn’t include — nuclear energy, which does not produce any greenhouse gases and runs 24/7 without intermittency issues; carbon capture and storage, which could help reduce the emissions from coal and natural gas plants; and bioenergy, which has also often been held out as critical to greening the electricity and transportation sectors.

But Clack and his colleagues contend that the study fails to prove that such a dramatic energy transition can be accomplished in an affordable way, in light of the constraints that occur when you have solar energy unavailable at night and wind energy also unavailable at certain times. They say it assumes a massive adoption of energy storage technologies that may not be feasible, and the possibility of huge volumes of hydroelectric generation.

The researchers actually suggest that 80 percent of the nation’s electricity could be produced without carbon dioxide in the future if you include nuclear energy and bioenergy combined with carbon capture and storage to sequester the emissions from the burning of biomass. But their conclusion on the Jacobson study is quite blunt.

“The study’s numerous shortcomings and errors render it unreliable as a guide about the likely cost, technical reliability, or feasibility of a 100% wind, solar, and hydroelectric power system,” they write. “It is one thing to explore the potential use of technologies in a clearly caveated hypothetical analysis; it is quite another to claim that a model using these technologies at an unprecedented scale conclusively shows the feasibility and reliability of the modeled energy system implemented by midcentury.”

Jacobson has, in turn, published a response in the journal and shared a line-by-line rebuttal to the study. In addition to his objections to how they have characterized his work, he adds that the authors are more focused on cutting carbon dioxide emissions than other social benefits that he and his co-authors care about. “We’re interested in air pollution, health, energy security, nuclear weapons proliferation, reducing the risk to society of all the dangerous considerations,” he said.

But Jacobson also suggests that he is being unfairly treated, writing, in a rebuttal he shared with The Washington Post, that “Clack’s analysis is riddled with intentional misinformation.” For instance, the critique asserts that Jacobson assumed that hydroelectric dams would have the capacity to generate over 1,000 gigawatts, or billion watts, of electricity, vastly more than exists today. Jacobson counters that that’s because the paper assumes that dams would add turbines, but only for peak usage; their average usage would still be much lower.

“They’re trying to make it as if it’s a model error,” said Jacobson. “And I have to respond to dozens of reporters who think that because they claim that it’s an error, it’s actually an error. It’s just ridiculous.”

Clack counters that it is indeed an error, “plain and simple.” “This notion that you can install 10 times the generating capacity at existing dams is a nonsense, because studies have been done to show that there is only about 12GW of capability for that in the US,” he said by email. There are numerous similarly complex claims and counterclaims at issue in the debate — which is part of the problem, says David Victor, an energy policy researcher at the University of California at San Diego and one co-author of the new critique.

“These are studies that seem to be anchored technically, lots of complexity to them, all of which point to the idea that the problem is solvable with a set of options that are frankly politically very palatable,” he said of Jacobson’s studies. That, says Victor, is why the research has been so influential.

“Our analysis suggests … that none of that work holds up,” Victor said. “So I can totally understand that emotions are high, but we have a duty as scientists to call the facts as we see them.”

Christopher Clack was previously with the National Oceanic and Atmospheric Administration’s Earth System Research Laboratory and the University of Colorado’s Cooperative Institute for Research in Environmental Sciences while authoring the paper, but now works with Vibrant Clean Energy.